The first thing you must do is match up your product’s variants with your product image’s alt tags. In order for this to work, the product’s variants must be exactly the same as the product image’s alt tags. The screenshot below shows you an example of a proper setup.
It’s important to note that you can only make a product association with one option. You can certainly have up to three options for your product (for example, I added a “Size” option here), but only one will affect what product image is shown. In step 3, you’ll see how to choose which option is tied to the product images.